Hybrid cannula and methods for manufacturing the same

ABSTRACT

A hybrid cannula may comprise a rigid portion overmolded with a flexible portion. The rigid portion at its proximal end may comprise a rigid flange for preventing the proximal end of the hybrid cannula from being pushed through the portal. The flexible portion may comprise a dam within the passage of the hybrid cannula, the dam defining interior spaces thereof between the proximal and distal ends of the hybrid cannula. The flexible portion&#39;s distal end may comprise a variety of features extending therefrom, including a flange and/or a cannulated tip. The flexible portion&#39;s proximal end may further comprise a membrane to prevent liquid from projecting during insertion of a tool into the dam and/or removal of the tool from the dam. The hybrid cannula can be useful in minimally invasive surgical procedures, including arthroscopic and endoscopic surgeries.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application relates to U.S. patent application Ser. No. 13/749,496,filed Jan. 24, 2013, entitled “HYBRID CANNULA AND METHODS FORMANUFACTURING THE SAME”, which is hereby incorporated by reference inits entirety.

TECHNICAL FIELD

This disclosure relates generally to surgical portal devices and, moreparticularly, to a hybrid cannula having a rigid portion overmolded witha flexible portion, the hybrid cannula being useful in minimallyinvasive surgical procedures, including arthroscopic and endoscopicsurgeries.

BACKGROUND

It is often preferable to perform a surgery as a minimally invasivesurgery (endoscopy or arthroscopy) rather than as an open surgery.Endoscopy and arthroscopy are performed through the use of portals.These portals, made through incisions in the skin and some portion ofunderlying tissue, are used to fill the abdomen with air, in the case ofendoscopy, and the surgical space with fluid, in the case ofarthroscopy.

For the duration of this disclosure minimally invasive surgery will bedescribed as it pertains to arthroscopic surgery; however, it is seenthat the disclosure extends into endoscopy as well as arthroscopy andthe invention disclosed should not be limited to arthroscopy.

A cannula is a medical device having an internal passage (or“cannulation”). A cannula can be inserted into a body, often to create apathway for elongated instruments to pass into and out of the surgicalspace. During arthroscopy, as mentioned before, fluid is inserted intothe surgical space (such as the shoulder) in order to pressurize anddistend the surgical space and improve visualization through thearthroscope. One reason a cannula is inserted into the portal is toprevent this fluid from escaping out of the body.

The cannula functions to prevent fluid from escaping from the surgicalspace while instruments are inserted through the passage in the cannulaas well as when no instruments are located in the cannula. This istypically performed by incorporating flexible dam/s with slits into thepassage in the cannula.

Cannulas generally consist of a proximal end, an elongated cannulatedbody, and a distal end.

FIGS. 1 a-1 b and 2 a-2 b depict views of a prior art cannula. A typicalcannula 100 is made of a rigid plastic while flexible dams 102 a and 102b are incorporated into the proximal end of the device and held in placeby cover 101. The rigidity of the cannula's elongated body 103 allowsthe device to simply be threaded using thread 104 through the portals intissue 10 and positioned over a site, such as depicted in FIG. 2 a.However, because this type of cannula has a large moment arm (MA), ithas a tendency to tip over when instruments are inserted through it, asdepicted in FIG. 2 b. For this reason, cannula 100 often has to be heldin place while inserting instruments through the device, which is notdesirable.

FIGS. 3 a-3 b and 4 depict views of another approach. Cannula 200 ismade of a flexible material, with a passage 219 along elongated body 201and a flexible dam 205 is incorporated into passage 219 along elongatedbody 201. Thin dam 203 may be attached at the proximal end of cannula200.

Flexible flanges 202 and 206 are found on the proximal and distal endsof the device, and the length of cannula 200 is approximately thethickness of the skin and some portion of underlying tissue. This devicehas a tendency to remain in place and upright during instrumentinsertion. However, the device is inserted through the portal using anon-standard method, which is not desirable. An example of anon-standard method may involve holding the distal end of cannula 200with the jaws of a grasping tool, advancing the jaws of the graspingtool and the distal end of cannula 200 together into the portal, andopening the jaws of the grasping tool to release cannula 200 from thegrasping tool after the distal end of cannula 200 exits the portal andcan be detected visually by surgical personnel.

SUMMARY OF THE DISCLOSURE

The disclosed methods and products detailed below serve in part toaddress the advantages and disadvantages of various types of cannulasdescribed above.

In one broad respect, embodiments disclosed herein may be directed to ahybrid cannula. A first portion may be formed from a first materialhaving a selected rigidity and include a proximal end having a flange, adistal end, and an internal passage or cannulation along the length ofthe first portion. A second portion may be formed from a second materialovermolded to the first portion. In one embodiment, the second portionmay include a first dam located inside the passage and approximatelyhalfway along a length of the hybrid cannula, and a membrane located inthe passage and near the flange, the second portion having a selectedflexibility. In some embodiments, the second portion extends beyond thedistal end of the first portion. In some embodiments, the second portionpartially overlaps the first portion. In some embodiments, the secondportion partially overlaps the first portion to include an externalthread. In some embodiments, the second portion comprises a flange on adistal end. In some embodiments, the first portion comprises an externalthread. In some embodiments, the external thread extends from the flangeto the distal end of the cannula. In some embodiments, the secondportion comprises thermoplastic elastomer.

In another broad respect, embodiments may be directed to a method forforming a hybrid cannula via an overmolding process involving a numberof portions of materials having different material properties. Forexample, in one embodiment of a hybrid cannula design, a method offorming a hybrid cannula may include forming a first portion of thehybrid cannula in a mold in a first molding process. In someembodiments, the first portion includes a proximal end, a distal end,and an internal passage or cannulation along the length of the hybridcannula. The method may further include positioning the first portion ina second mold and overmolding a second portion of the hybrid cannula ina second molding process. The second portion may include a first damlocated inside the internal passage approximately halfway along a lengthof the cannula and a membrane located in the internal passage in thesecond portion having a selected flexibility. In some embodiments,forming a first portion comprises forming an external thread on aportion of the hybrid cannula. In some embodiments, forming a secondportion comprises forming an external thread along a length of thehybrid cannula. In some embodiments, the method may further includepositioning the first portion and second portion of the hybrid cannulain a third mold and forming a third portion in a third molding process.In some embodiments, the third portion comprises a thread on the outsideof the first portion.

In another broad respect, embodiments may be directed to a surgicalmethod. The method may include forming a portal in soft tissue in apatient and advancing a hybrid cannula into the portal. The hybridcannula may comprise a first portion manufactured from a first materialhaving a selected rigidity, and a second portion formed from a secondmaterial overmolded to the first portion. The first portion may includea proximal end having a flange, a distal end, and an internal passagealong the length of the hybrid cannula. The second portion may include afirst dam located inside the passage approximately halfway along alength of the hybrid cannula and a membrane having a selectedflexibility. In some embodiments, advancing the hybrid cannula comprisespositioning the hybrid cannula in the portal to position the dam withinthe soft tissue. In some embodiments, advancing the hybrid cannulacomprises engaging the hybrid cannula with a tool and rotating the toolto engage a thread on the hybrid cannula with the soft tissue. In someembodiments, the hybrid cannula may be advanced through the portalwithout rotating the hybrid cannula. In some embodiments, advancing ahybrid cannula into or through a portal may include a translationalmovement, a rotational movement, or a combination thereof. In someembodiments, advancing the hybrid cannula comprises advancing the hybridcannula until the flange on the proximal end contacts the soft tissue.In some embodiments, the method may further include advancing one ormore instruments through the passage in the hybrid cannula.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings form part of the present specification and areincluded to further demonstrate certain aspects of the invention. Theinvention may be better understood by reference to one or more of thesedrawings in combination with the detailed description of specificembodiments presented herein.

It is to be noted, however, that the appended drawings illustrate onlyexemplary embodiments of the invention and are therefore not to beconsidered limiting of its scope for the invention which may admit toother equally effective embodiments. In addition, although the figuresmay depict embodiments wherein the components represent differentdevices or locations, they can be combined into a single device orlocation. Also, a single component may be comprised of a combination ofcomponents.

FIG. 1 a depicts a rigid cannula.

FIG. 1 b depicts the cannula of FIG. 1 a in an exploded view.

FIG. 2 a depicts the cannula of FIG. 1 a inserted through the softtissue.

FIG. 2 b depicts the cannula of FIG. 1 a inserted through the softtissue, while the moment placed on it by the force of inserting aninstrument through the cannula has caused it to begin to tilt.

FIG. 3 a depicts a flexible cannula.

FIG. 3 b depicts the cannula of FIG. 3 a in an exploded view.

FIG. 4 depicts a cross-sectional view of the cannula of FIG. 3 a.

FIG. 5 depicts an isometric view of one embodiment of a hybrid cannula.

FIG. 6 depicts an exploded view depicting portions of one embodiment ofa hybrid cannula.

FIGS. 7 a and 7 b depict a top view and a cross-sectional view of oneembodiment of a hybrid cannula.

FIGS. 8 a and 8 b depict a top view and a cross-sectional view of aportion of one embodiment of a hybrid cannula.

FIGS. 9 a and 9 b depict a cross-sectional view and a top view ofanother portion of one embodiment of a hybrid cannula.

FIG. 10 depicts a flow diagram of one example method of manufacturing ahybrid cannula.

FIG. 11 depicts an isometric view of one embodiment of a hybrid cannula.

FIG. 12 depicts an exploded view depicting portions of one embodiment ofa hybrid cannula.

FIGS. 13 a and 13 b depict a top view and a cross-sectional view of oneembodiment of a hybrid cannula.

FIG. 14 depicts an isometric view of one embodiment of a hybrid cannula.

FIGS. 15 a and 15 b depict a top view and a cross-sectional view of oneembodiment of a hybrid cannula.

FIG. 16 a depicts a side view of one embodiment of a hybrid cannula anda tool useful for inserting a cannula.

FIG. 16 b depicts a side view of one embodiment of a hybrid cannulacoupled with a tool useful for inserting a cannula.

FIG. 17 a depicts a cross-sectional view of one embodiment of a hybridcannula inserted through thick soft tissue.

FIG. 17 b depicts a cross-sectional view of one embodiment of a hybridcannula inserted through thin soft tissue.

FIGS. 18 a and 18 b depict side and cross-sectional views of oneembodiment of a hybrid cannula.

FIGS. 19 a and 19 b depict side and cross-sectional views of oneembodiment of a hybrid cannula.

DETAILED DESCRIPTION

Embodiments of hybrid cannulas disclosed herein can overcome theshortcomings of conventional cannulas. Using manufacturing methods nottraditionally utilized for cannulas, a new device may be created to havethe ability, among others, to remain stable during instrument insertionand to be inserted through the portal using traditional methods. Thoseskilled in the art will recognize that the invention can be used in botharthroscopic and endoscopic surgery without departing from the spirit orscope of the invention.

Referring first to FIG. 1 a, a typical arthroscopic cannula 100, whichis fully assembled, is depicted. Most generally, arthroscopic cannula100 consists of distal end 110, cover 101, and proximal end 105 wherefunctioning dams 102 a and 102 b are attached to the device, as shown inFIG. 1 b. FIG. 1 b depicts an exploded view of cannula 100.

The following steps outline a general method for manufacturing cannula100, although variations to this method may exist.

The cannula's elongated body 103 and cover 101 may be manufacturedseparately from a similar rigid material using, for instance, separatesingle-shot molding processes. Elongated body 103 may be formed withstop cock 107 to accommodate attachments such as inflow or outflow pumptubing. Dams 102 a and 102 b may be manufactured from a flexiblematerial and function to prohibit fluid from passing through cannula100. Flexible dams 102 a and 102 b may be made in various ways. Forexample, dams 102 a and 102 b can be manufactured via molding and/or diecutting processes. In a molding process, dams 102 a and 102 b are firstmolded. Slits 108 and 109 are then created in dams 102 a and 102 b. In adie cutting process, a flat sheet of flexible material such as rubber iscut into a circular shape using a die. The die may also cut slits 108and 109 into dams 102 a and 102 b, or a secondary slitting operationcould be used to create slits 108 and 109 in dams 102 a and 102 b. Diecutting the flexible material may be the preferred method to manufacturedams 102 a and 102 b because it is a relatively inexpensive process ascompared to molding.

Traditionally, cannula 100 components are assembled and fixed togetherusing methods such as adhesives and/or mechanical fixation. It isimportant to note that elongated body 103, dams 102 a and 102 b, andcover 101 must be assembled together in a secondary operation.Specifically, the axis of dam 102 a is rotationally offset from the axisof dam 102 b so that the dams' slits 108 and 109 are not aligned. Dams102 a and 102 b are placed between elongated body 103 and cover 101.Elongated body 103 and cover 101 are rigidly fixed to one another usingany number of fixations including but not limited to adhesives ormechanical fixation.

Referring next to FIG. 3 a, another arthroscopic cannula 200 may beflexible and have flanges on both ends. In FIG. 3 b, an exploded view ofcannula 200 exposes components of which cannula 200 comprises. Elongatedbody 201 with flanges 202 and 206, and thin dam 203 are typically madefrom the same material, which may be a flexible rubber, silicone, or thelike. FIG. 4 depicts a cross-sectional view of cannula 200, showing dam205 positioned inside passage 219 in elongated body 201.

The following steps outline a general method for manufacturing cannula200, although variations to this method may exist.

Cannula 200 may be manufactured by a single shot molding process. Themold from the single shot molding process includes features to accountfor flanges 202 and 206 as well as dam 205, which is integral toelongated body 201. As a result of this single shot molding process, dam205 and elongated body 201 must be manufactured from the same flexiblematerial, such as rubber, silicone, or the like. This allows for dam 205to remain flexible and maintain similar properties as dams 102 a and 102b in cannula 100. Additionally, using this process enables dam 205 to beintegral to elongated body 201 and be located inside passage 219 ofelongated body 201. After molding, a secondary slitting operation isthen used to create slits in dam 205. Thin dam 203 may be manufacturedfrom a number of processes. One process is to mold thin dam 203 with asmall aperture 204 or die cut small aperture 204 after molding thin dam203, while a second method is to die cut thin dam 203 with a smallaperture 204 from a sheet of flexible material such as rubber.

Thin dam 203 may be attached to flange 202 on elongated body 201. Thismay be accomplished by any number of chemical, mechanical, or thermalmethods, including but not limited to a mechanical fit.

Cannula 200 is characterized by several disadvantages. Some of thesedisadvantages include cannula 200 may be too flexible for use withtraditional insertion procedures, cannula 200 may move up and downwithin the portal during instrument insertion and/or removal, or thelike.

Common features of both cannula 100 and cannula 200 are the flexibledams. In the case of the rigid cannula 100, general practice is toassemble dams 102 a and 102 b to rigid parts 101 and 103 of cannula 100using secondary operations. In the case of flexible cannula 200,elongated body 201 and flanges 202 and 206 are molded from the samematerial as dam 205, eliminating the need to assemble dam 205 toelongated body 201. As will be shown below, embodiments disclosed hereinleverage manufacturing methods not typically used in manufacturingcannulas, in order to create a device which can provide some of theadvantages of cannula 100 and cannula 200 without some of theirrespective drawbacks.

In one embodiment, a hybrid cannula may include a rigid portion with aflexible portion formed with a dam and/or membrane in an internalpassage of the cannula. The flexible portion may be overmolded onto therigid portion. In one embodiment, the rigid portion and the flexibleportion may partially overlap as a result of an overmolding process.

One example of a hybrid cannula is depicted in FIG. 5. Hybrid cannula300 may comprise proximal end 310 and distal end 320. An exploded viewof hybrid cannula 300 is depicted in FIG. 6. First portion 400 of hybridcannula 300 may be made of a material with selected rigidity so that itis rigid enough to be easily inserted or positioned in a patient usingtraditional insertion methods, and may be formed to have an elongatedshape or profile from proximal end 310 to distal end 320 (as seen inFIG. 5). Second portion 500 of hybrid cannula 300 may be flexible andcontain one or more features to prevent fluid leakage and/or squirting.

FIGS. 7 a and 7 b depict a top view and a cross-sectional view of hybridcannula 300 in which second portion 500 may be formed partially insidefirst portion 400. This may be established in any number of waysincluding but not limited to overmolding second portion 500 to firstportion 400. As depicted in FIGS. 7 a and 7 b, hybrid cannula 300 havingpassage 508 formed therein may include first portion 400 which mayinclude an outer surface formed with thread 404 and flange 402 havingouter radius R_(O) and having inner radius R_(I). The ratio ofR_(O)/R_(I) may be selected to minimize the overall size of hybridcannula 300 while still maintaining its structural integrity. In someembodiments, the ratio may be selected to minimize the overall size offlange 402.

Second portion 500 may be formed from various materials. Second portion500 may be formed in first portion 400 and include dam 504 havingslit(s) 509, thin membrane 502, and walls 503 a and 503 b. Dam 504 mayhave a thickness t_(D), thin membrane 502 may have a thickness t_(M),and walls 503 a and 503 b may have a thickness t_(W). Thin membrane 502may be formed with slots 506 and positioned at proximal end 310 b.Opening 507 may also be formed in membrane 502. Opening 507 and slots506 may be configured to allow for a core pin or tool necessary formolding to maintain structural integrity during the manufacturingprocess. As depicted in FIG. 7 a, dam 504 may be visible through opening507, including slits 509. Opening 507 and slots 506 and slits 509 may bealigned about a central or longitudinal axis A, and dam 504 and thinmembrane 502 may be oriented relative to each other such that slots 506and slits 509 do not align. Distal end 320 b of second portion 500 mayor may not extend over distal end 320 a of first portion 400.Additionally, proximal end 310 b of second portion 500 may or may notextend past proximal end 310 a of first portion 400.

Hybrid cannula 300 may be manufactured to a number of different overalllengths. A correctly sized length of hybrid cannula would be selectedfor use during the arthroscopy based on the thickness of the softtissues that the portal extends through.

FIGS. 8 a and 8 b depict a top view and a cross-sectional view of firstportion 400 of hybrid cannula 300. Embodiments of first portion 400 mayextend between proximal end 310 a and distal end 320 a of hybrid cannula300. Additionally, there may be flange 402 at proximal end 310 a andthread(s) 404 along the outside of first portion 400.

First portion 400 of hybrid cannula 300 may be composed of one materialor several materials. Additionally, each feature of first portion 400may be made of only one material or of several materials. The materialsof each feature may be flexible, rigid, or semi-rigid. Examples of rigidmaterials that may be used in first portion 400 and may be appropriatefor use in surgery may include, but are not limited to polycarbonate,polyetheretherketone (PEEK), and acrylonitrile butadiene styrene (ABS).Examples of flexible materials that may be used in first portion 400 maybe appropriate for use in surgery and may include, but are not limitedto, silicone, thermoplastic elastomer, polyurethane, and rubber. Othermaterials may be used for overmolding onto, for example, titanium andstainless steel. For both flexible and rigid materials, it may bebeneficial for the material to include colorants and/or to be partiallytransparent. Plastic or stainless steel are generally accepted by theorthopedic community. Some embodiments of hybrid cannula 300 disclosedherein can be lighter in weight than a conventional cannula, such ascannula 100. The reduction in weight of hybrid cannula 300 relative tocannula 100 may be caused by the elimination and/or size reduction ofone or more features of cannula 100. For example, hybrid cannula 300 maynot include a stop cock such as stop cock 107 of cannula 100. As anotherexample, selected for the same patient, hybrid cannula 300 may beshorter in length relative to cannula 100.

Proximal end 310 of hybrid cannula 300 may include flange 402. Hybridcannula 300 can be inserted in a manner similar to cannula 100 describedabove, and various features of hybrid cannula 300 can provide severaladditional advantages. For example, flange 402 at proximal end 310 ofhybrid cannula 300 may prevent hybrid cannula 300 from being overinserted by providing a surface 411 to press against the skin, stoppinghybrid cannula 300 from being inserted further than the base of flange402. Additionally, flange 402 provides a surface for features 401 whichallow an insertion instrument (an example is depicted in FIGS. 16 a and16 b, discussed below) to contact hybrid cannula 300 and insert itthrough the portal. Features 401 may be any size or shape which allowsfor an opposing shape or complimentary feature on an insertioninstrument to insert and provide a resistance to the torque and/or forceplaced on hybrid cannula 300 during insertion of hybrid cannula 300through the portal. Additional advantages will be apparent to thoseskilled in the art.

First portion 400 may be cannulated or otherwise include passage 419with opening 410 to allow instruments to pass through duringarthroscopy. Inner surface 406 may also be appropriately shaped formaterial to adhere to it. Additionally, first portion 400 may or may notbe uniformly thick and could have a number of features built into innersurface 406 or outer surface 407, including but not limited to ribbing,holes, steps, threads, and slots.

External threads 404 may function to aid in insertion threading ofhybrid cannula 300 into the soft tissue surrounding the portal.Additionally, external threads 404 may function to hold hybrid cannula300 in place in the soft tissue throughout the surgery, including duringinstrument insertion and removal. External threads 404 may start at ornear flange 402 and may lead out of the hybrid cannula at or near distalend 320 a of first portion 400. External threads 404 may start anydistance past flange 402 and end any distance before distal end 320 a.For example, one skilled in the art would appreciate that in someapplications it would be beneficial for only the portion near distal end320 a to contain external threads. External threads 404 shown may have aconstant pitch and profile; however, a variable pitch and/or a variableprofile of external threads 404 could be used to aid in engaging thesoft tissue. Additionally, angle Θ_(S) of profile of external threads404 may be generally perpendicular to or angled relative to longitudinalaxis A. Additionally, the profile of thread 404 may be any shapeincluding but not limited to trapezoidal, circular, rectangular,triangular, ovular, and asymmetric shapes.

FIGS. 9 a and 9 b depict a cross-sectional view and a top view of secondportion 500 of hybrid cannula 300. Second portion 500 may compriseproximal end 310 b, body regions or bodies 503 a-503 b, and distal end320 b. Second portion 500 may include passage 508 from thin membrane 502at proximal end 310 b along the length of hybrid cannula 300 to opening511 at distal end 320 b. The inner diameter of passage 508 may beconstant along the length of second portion 500 or may vary. In someembodiments, the inner diameter of passage 508 may vary due to thicknesst_(W) of walls 503 a or 503 b. In some embodiments, the inner diameterof passage 508 may vary due to the inner diameter of first portion 400.

At proximal end 310 b of second portion 500, membrane 502 (also referredto as a squirt membrane) may be found. Thickness t_(M) of membrane 502can be of any suitable thickness, depending upon the elasticity,durometer, and/or strength of the material used. Examples of a suitablethickness may range from about 0.25 mm to about 2 mm. Thickness t_(M) ofthe membrane can be about the same as or less than thickness t_(D) ofdam 504.

A purpose of squirt membrane 502 may include preventing fluid from beingexpelled from (“squirting out of”) hybrid cannula 300 during instrumentinsertion or removal. For example, when an arthroscopic instrument ispassed through or removed from hybrid cannula 300 the pressure behinddam 504 may cause fluid to squirt through dam 504 and around theinstrument. Squirt membrane 502 may provide a secondary surface toprevent the fluid from exiting proximal end 310 b of hybrid cannula 300and striking the surgeon. The thickness t_(M) of squirt membrane 502 maybe small to prevent significant resistance to the arthroscopicinstrument when the instrument is inserted through the device. Squirtmembrane 502 may be flexible so that the movement of the instrumentwithin hybrid cannula 300 is not restricted.

As illustrated in FIG. 9 a, dam 504 may be positioned in passage 508between proximal end 310 b and distal end 320 b of second portion 500.The thickness of the dam can be about the same as or more than thethickness of squirt membrane 502 described above. At distal end 320 b ofsecond portion 500 of hybrid cannula 300, a feature which may allowsecond portion 500 to be molded throughout the entire length of firstportion 400 may be found. For example, protrusion 707 at distal end 320b may be a feature that can be used as a seal-off during overmolding ofsecond portion 500 onto first portion 400. It can be appreciated that anumber of different types of seal-offs may be used distal or proximal todam 504 in order to overmold second portion 500 onto first portion 400.A seal off may be on squirt membrane 502 during overmolding as well. Inembodiments in which the squirt membrane is not present, seal-offs maybe on walls 503 a and 503 b, both distal and proximal to dam 504.

Second portion 500 of hybrid cannula 300 may be composed of one materialor several materials. The materials of each feature may be flexible,semi-rigid, or rigid. Examples of these flexible and semi-rigidmaterials that may be used to manufacture second portion 500 and may beappropriate for use in surgery include, but are not limited to,silicone, thermoplastic elastomer, polyurethane, and rubber. Examples ofrigid materials that may be used in second portion 500 and may beappropriate for use in surgery may include, but are not limited topolycarbonate, polyetheretherketone (PEEK), and acrylonitrile butadienestyrene (ABS). Other materials may be overmolded onto, for exampletitanium and stainless steel. It may also be beneficial for thematerials to include colorants and/or to be partially transparent.

In second portion 500, squirt membrane 502 and dam 504 may be connectedby body region 503 a. However, it may be found in some embodiments ofsecond portion 500 body regions 503 a-503 b may not connect one featureto another. For example, in one embodiment possibility, protrusion 707may be connected to dam 504 by body region 503 b, but squirt membrane502 might not be connected to dam 504 by body region 503 a. Therefore,dam 504 and squirt membrane 502 may be formed during two separateprocesses.

As mentioned above, proximal end 310 b may include squirt membrane 502.An advantage of squirt membrane 502 is that it may prevent fluid fromsquirting out of hybrid cannula 300 during instrument insertion orremoval. When an arthroscopic instrument is passed through hybridcannula 300, fluid pressure behind dam 504 may cause fluid to squirtthrough dam 504 and around the instrument. Squirt membrane 502 may bethin and present little resistance to the arthroscopic instrument whenthe instrument is inserted through or removed from passage 508 of hybridcannula 300. Squirt membrane 502 may be flexible so that the movement ofinstruments within passage 508 of hybrid cannula 300 is not restricted.Additionally, slots 506 may be created through squirt membrane 502 sothat instruments may pass through squirt membrane 502. As depicted inFIG. 9 b, squirt membrane 502 may be formed with opening 507 and/or withslots 506. Opening 507 and slots 506 may individually or togethercombine to have any shape, length, thickness, orientation, andcombination thereof, including but not limited to triangle-like slits, acircular hole, a straight slit, an ovular opening, slots and knifeslits.

In one embodiment of hybrid cannula 300, body 503 a-503 b of secondportion 500 may be integral with one or more of squirt membrane 502, dam504, and protrusion 707. Body 503 a or 503 b may be sufficiently strongto hold membrane 502 and/or dam 504 and/or to more securely attachsecond portion 500 to first portion 400. Also, thickness t_(W) of body503 a or 503 b may be thin so that the inner diameter or cannulation ofsecond portion 500 remains as large as possible to allow for a varietyof diameters of arthroscopic instruments to pass through hybrid cannula300.

Dam 504 may prevent fluid from passing through hybrid cannula 300during, before, and after arthroscopic instruments are passed throughhybrid cannula 300. Dam 504 may be preferably thick enough to preventfluid from leaking but not so thick that it is difficult for the surgeonto pass the arthroscopic instruments through dam 504. Dam 504 maycontain openings such as slits 509 to allow instruments to pass throughdam 504. These openings flex around an instrument when an instrument ispassed through dam 504 and close when dam 504 is in its stable state.These openings in combination with the shape of dam 504 may take theform of any number of shapes, lengths, thicknesses, orientations, andcombination thereof, including but not limited to, circular hole(s),ovular opening(s), knife slit(s), tri-slits, duck bill(s), straightslit, quad-slits, overlapping flaps, and small aperture(s). These slitsmay preferably be long enough to allow instruments to pass though dam504 without damaging dam 504, even when the instrument has a diameteronly slightly smaller than the inner diameter of passage 508 of hybridcannula 300. Although only one dam 504 is shown in this configuration ofsecond portion 500 of hybrid cannula 300, an embodiment of a hybridcannula may comprise two or more dams to be located within secondportion 500 thereof.

Additionally, the location of dam 504 within the length of hybridcannula 300 may be anywhere within passage 508 of second portion 500 butmay preferably be distal to squirt membrane 502. In one embodiment, dam504 may be located near the middle of hybrid cannula 300 betweenproximal end 310 b and distal end 320 b of second portion 500. The damlocation may determine the length of the moment arm acting on the hybridcannula during instrument insertion and removal. It may be preferablethat dam 504 be located in hybrid cannula 300 such that dam 504 can bepositioned at or below the level of the skin, no matter how deep hybridcannula 300 is inserted. However, if dam 504 is too close to distal end320 of hybrid cannula 300, when articulating instruments are opened,significant leaking or squirting may occur.

The following steps outline a general method for manufacturing hybridcannula 300, although variations to this method may exist. Embodimentsdisclosed herein may be manufactured using different processes toproduce hybrid cannula 300 having a substantially rigid first portion400 and substantially flexible second portion 500 with passage 508 whichmay include dam 504, squirt membrane 502, and other features includedtherein.

Hybrid cannula 300 may be manufactured by overmolding second portion 500onto first portion 400, so that no additional assembly is needed. Theprocess of overmolding allows for a cannula with a substantially rigidbody composed of one material and a dam composed of another material tobe manufactured without the need to secondarily assemble the dam to thebody of the cannula.

FIG. 10 depicts a flow diagram illustrating one example method formanufacturing a hybrid cannula. In step 1010, a material may be selectedfor first portion 400 of hybrid cannula 300. As mentioned above, firstportion 400 may be manufactured from materials selected for a desiredrigidity, with selected features such as threads 404, flange 402, andthe like on the outer surface, and may include steps, tapers, surfaceroughness or other features on the inner surface for contact with secondportion 500. The selection of one or more materials for first portion400 may depend on one or more of an intended length of hybrid cannula300, a desired inner diameter of hybrid cannula 300, a surgicalprocedure in which hybrid cannula 300 is to be used, an expected fluidpressure, and the like. Material selection may also factor in weight ordensity of a material, radioluminescence, color, and transparency.

In step 1020, first portion 400 is manufactured, such as by injectionmolding or other processes for shaping plastic, metals, ceramicmaterials or other biocompatible materials known and applicable tobiomedical components. In some embodiments, first portion 400 ismanufactured through liquid injection molding of a rigid plastic usingany number of core pins and mold cavities. For example, material may beinjected into a mold and cooled or cured to produce first portion 400having selected features. After first portion 400 has been molded, thecore pins are removed. Steps 1010 and 1020 may be repeated as necessaryuntil all features are formed in first portion 400. First portion 400may undergo secondary processes such as machining or texturing aspreparation for joining with second portion 500.

In step 1030, a material may be selected for second portion 500. Secondportion 500 may be manufactured from one or more materials selected fora desired flexibility, smoothness, surface friction, elasticity and thelike and for contact with first portion 400.

In step 1040, first portion 400 may be positioned in a second mold. Newcore pins may be placed into first portion 400 so that an open spaceremains between first portion 400 and the core pins, except at thepoints where second portion 500 is meant to begin and end against firstportion 400, in order to create the desired features which may includesquirt membrane 502 and/or dam 504 features. As an example, in oneembodiment, the selected material can be liquid injection molded intoempty space in first portion 400 through the process of overmolding.Steps 1030 and 1040 may be repeated as necessary until all features areformed in second portion 500. The material forming second portion 500adheres to first portion 400, and the core pins are removed from thedevice leaving second portion 500 permanently fixed to first portion400. Secondary operations on hybrid cannula 300 may include, but are notlimited to, slitting dam 504 located in second portion 500. Furthermachining or manufacturing processes may be used to customize hybridcannula 300 for a particular use or patient.

Other embodiments of hybrid cannula 300 may provide additional features,including features relating to a distal end. Example features that maybe included in embodiments of hybrid cannula 300 will now be described.

FIG. 11 depicts an embodiment of hybrid cannula 300, which comprisessimilar features as discussed above, and further includes portion 360 ofsecond portion 500 extending beyond the distal tip of first portion 400.Portion 360 may be flexible, semi-rigid, transparent, or have some othercharacteristic different than the distal tip of first portion 400. Insome embodiments, hybrid cannula 300 having portion 360 may allow firstportion 400 to be reduced in length, which may be advantageous duringinsertion, surgery, or removal.

FIG. 12 depicts an embodiment of hybrid cannula 300 as seen in FIG. 11,in which second portion 500 may include portion 360 having transitionsection 363. Transition section 363 may provide additional adhesionbetween second portion 500 and first portion 400, as well as provide aseal off feature which may be necessary for the overmolding process. Inone embodiment, dam 504 may be located at seam 515 of second portion500. The distance between seam 515 and transition section 363 or distalend 320 b may be shorter than the distance between, for example, dam 504and proximal end 310 b (see FIG. 7 b).

FIGS. 13 a and 13 b depict a top view and a cross-sectional view of anembodiment of hybrid cannula 300 as seen in FIGS. 11 and 12 in whichdistal end 320 b of second portion 500 has been extended past distal end320 a of first portion 400. It may be preferable for end portion 360 tobe manufactured from a flexible material described previously. This mayallow the surgeon to open articulating instruments while part of thefunctional tip of the articulating instrument is located within hybridcannula 300. End portion 360 may stretch and expand while the instrumentis articulating. It may be preferable for end portion 360 to be flexibleenough for the material to easily stretch during instrument articulationbut strong enough to prevent tearing of the material. The range offlexibility is dependent upon the material. Likewise, the distance thatend portion 360 at distal end 320 b of second portion 500 extends pastdistal end 320 a of first portion 400 may vary from implementation toimplementation.

FIG. 14 depicts an isometric view of an embodiment of hybrid cannula 300having flange 365 formed at the distal end of second portion 500 (seeFIG. 15 b) and thread 404 extending only partially along the length offirst portion 400.

FIGS. 15 a and 15 b depict a top view and a cross-sectional view of anembodiment of hybrid cannula 300 as seen in FIG. 14 in which secondportion 500 includes flange 365 extending past first portion 400. It maybe preferable that second portion flange 365 be manufactured from aflexible material described previously. Flange 365 may ensure thathybrid cannula 300 remains flush to the inner surface of the softtissue. Flange 365 may have the benefit of staying out of the surgicalspace as well as potentially improving the field of vision in thesurgical space. Flange 365 may have any diameter or shape including butnot limited to circular, triangular, and fan shapes and may be beveledor otherwise shaped to allow ease of insertion or removal from apatient. Flange 365 may be thin enough to fold up along the sides offirst portion 400 when hybrid cannula 300 is inserted through a portal.Flange 365 may be strong enough not to tear and to hold its originalshape once hybrid cannula 300 has been inserted. Additionally, flange365 may include slits or gaps (not shown) to aid flange 365 in foldingup along the sides of first portion 400 when hybrid cannula 300 isinserted through a portal.

On first portion 400 of hybrid cannula 300 thread 404 may terminate nearto or away from the distal end of first portion 400. Additionally,second portion 500 of hybrid cannula 300 may extend past externalthreads 404. External threads 404 may hold hybrid cannula 300 in thesoft tissue while the distal end of first portion 400 of hybrid cannula300 may allow a smooth surface for flange 365 to rest against duringinsertion of hybrid cannula 300 through the portal. This may preventexcessive protruding of flange 365 against first portion 400 of hybridcannula 300 during insertion of the device through the portal.

FIGS. 16 a and 16 b depict side views of one embodiment of hybridcannula 300 and an obturator 90 (also referred to as a trochar ordilator) useful for inserting hybrid cannula 300 into a patient. As seenin FIG. 16 a, obturator 90 may have a central shaft 91 having a lengthsuch that end 92 extends beyond a distal end of hybrid cannula 300, andend 92 may be pointed or otherwise shaped for ease of insertion throughthe soft tissue. Features 93 on obturator 90 may engage hybrid cannula300 such that by rotating obturator 90 about a central or longitudinalaxis, threads 404 of hybrid cannula 300 may engage the soft tissue andadvance hybrid cannula 300 into position. Obturator 90 may also be usedto remove hybrid cannula 300 or adjust positioning or orientation ofhybrid cannula 300 during use. Other insertion methods may be utilized.For example, a long thin metal rod (referred to as a switching stick) isplaced through an incision in the skin. The hybrid cannula is placedover the cannulated obturator (the obturator has a hole along its axis).The assembled hybrid cannula and obturator are placed over the switchingstick and the hybrid cannula is threaded, pushed or otherwise advancedinto the soft tissue. The switching stick is removed and the obturatoris removed, leaving the hybrid cannula behind.

Attention is now turned to FIGS. 17 a-17 b which may exemplify the finalposition of hybrid cannula 300 after inserting it through the softtissue. Other after-insertion positions of hybrid cannula 300 may alsobe possible and anticipated. FIG. 17 a depicts soft tissue 800 havingouter surface 801 and inner surface 802. FIG. 17 b depicts soft tissue900 with outer surface 901 and inner surface 902. It can be seen thatsoft tissue 800 in FIG. 17 a is thicker than soft tissue 900 in FIG. 17b. In both cases, hybrid cannula 300 is shown inserted through theportal made in soft tissues 800 and 900 and, in both cases, dam 504 islocated below outer surface 801 or 901 of the soft tissue. This maydecrease the moment arm of hybrid cannula 300 and may further preventthe hybrid cannula from falling over, thereby solving a problem commonin cannula 100. The moment arm generally refers to the distance from thecenter of the soft tissue to the point at which an instrument placesforce on hybrid cannula 300. The location of dam 504 may determine or atleast influence the location of the force causing the moment arm.

In one embodiment of hybrid cannula 300, such as depicted in FIG. 17 a,proximal flange 402 of hybrid cannula 300 may fit flush against outersurface 801 of soft tissue 800 while distal end 320 of hybrid cannula300 just extends past inner surface 802 of soft tissue 800. In thiscase, hybrid cannula 300 is just long enough to be used. If soft tissue800 is thicker, a longer hybrid cannula 300 may need to be used.

In one embodiment of hybrid cannula 300, such as depicted in FIG. 17 b,proximal flange 402 of hybrid cannula 300 abuts or is proximal to outersurface 901 of soft tissue 900 while distal end 320 of hybrid cannula300 just extends past inner surface 902 of soft tissue 900. In thiscase, hybrid cannula 300 fits the soft tissue since external threads 404are engaging soft tissue 900, distal end 320 of hybrid cannula 300extends just past inner surface 902 of soft tissue 900, and dam 504 ofhybrid cannula 300 remains subcutaneous, subdermal, intramuscular, orotherwise beneath outer surface 901 of soft tissue 900. If soft tissue900 is thinner, a shorter hybrid cannula 300 may need to be used inorder for the dam to remain subcutaneous, subdermal, intramuscular, orotherwise beneath outer surface 901 of soft tissue 900.

One method for using hybrid cannula 300 may involve preparing thesurgical site. For example, an x-ray, MRI, or other imaging system maybe used to determine the thickness of soft tissue 900 and other tissuenear the desired surgery site. Depending upon the thickness of softtissue, hybrid cannula 300 may be selected or prepared accordingly forinsertion. In some embodiments, a kit may include different lengths,inner diameters of a passage, dam positions, dam thicknesses, squirtmembrane thicknesses, etc. of hybrid cannula 300.

Selection of a desired hybrid cannula 300 may be based on a feature ofhybrid cannula 300. For example, a hybrid cannula 300 may be selected toensure that a dam is positioned at some point in the tissue, such asapproximately half way, close to the surface, close to the surgicalsite, or some point in between.

As mentioned above, embodiments disclosed herein may be manufacturedsuch that a variety of hybrid cannula 300 options exist with dam 504positioned in various locations within passage 508 of second portion500. In some embodiments, hybrid cannula 300 may be cut or otherwisemodified in the operating room for a desired surgery.

Advancement of hybrid cannula 300 into a patient may involve translationor rotation or some combination thereof. For example, hybrid cannula 300may be pushed or threaded into soft tissue. In some embodiments, anarthroscope or other visualization tool may be advanced into the patientto see how far hybrid cannula 300 needs to be advanced. In someembodiments, markings on hybrid cannula 300 may enable advancement ofhybrid cannula 300 to a desired depth. Example markings may include, butare not limited to, tool markings, laser lines, threads on the exteriorof first portion 400 of hybrid cannula 300, etc. In one embodiment, anarthroscope or other visualization tool may be used to determine whetherhybrid cannula 300 has been inserted properly through the soft tissue.

In some embodiments, hybrid cannula 300 may be advanced until the distalend contacts a selected body part, opening, space, or tissue. Forexample, in some embodiments in which hybrid cannula 300 has a flexibledistal end, the tip may be advanced until the tip contacts the desiredtissue, which may allow a surgeon to operate without debris approachingthe surgical site as the surgeon is operating.

Once advanced to a desired depth, one or more tools may be advanced intothe patient via a passage in the hybrid cannula.

Removal of hybrid cannula 300 may include removal of tools from insidepassage 508, rotating and/or pulling hybrid cannula 300 to disengagethreads 404 from tissue, and removing hybrid cannula 300 from thepatient. One or more sutures may be applied to close the incision.

FIGS. 18 a-18 b and FIGS. 19 a-19 b depict embodiments of hybrid cannula300 which may be manufactured using multiple overmolding passes and/ormanufactured to have selected features. As depicted in FIGS. 18 a and 18b, first portion 400 may be formed in a first process and second portion500 may be overmolded or otherwise formed in a second process to forminternal features such as dam 504 as well as external features such asthread 1804. As depicted in FIGS. 19 a and 19 b, more than oneovermolding process may be used to manufacture features onto hybridcannula 300. For example, first portion 400 may be formed in a firstprocess. A first overmolding process may be used to form dam 504 andother generally internal features of second portion 500, and a secondovermolding process may be used to manufacture thread or ribbing 600.Other features or molding processes may be useful.

The detailed description and the specific examples described above,while indicating the preferred embodiments, are given by way ofillustration only and not by way of limitation. Descriptions of knownmaterials and manufacturing techniques may be omitted so as not tounnecessarily obscure the disclosure in detail. Various substitutions,modifications, additions and/or rearrangements within the spirit and/orscope of the underlying inventive concept will become apparent to thoseskilled in the art from this disclosure.

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having,” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a process,product, article, or apparatus that comprises a list of elements is notnecessarily limited only those elements but may include other elementsnot expressly listed or inherent to such process, process, article, orapparatus.

Furthermore, the term “or” as used herein is generally intended to mean“and/or” unless otherwise indicated. For example, a condition A or B issatisfied by any one of the following: A is true (or present) and B isfalse (or not present), A is false (or not present) and B is true (orpresent), and both A and B are true (or present). As used herein,including the accompanying appendices, a term preceded by “a” or “an”(and “the” when antecedent basis is “a” or “an”) includes both singularand plural of such term, unless clearly indicated otherwise (i.e., thatthe reference “a” or “an” clearly indicates only the singular or onlythe plural). Also, as used in the description herein and in theaccompanying appendices, the meaning of “in” includes “in” and “on”unless the context clearly dictates otherwise.

It will also be appreciated that one or more of the elements depicted inthe drawings/figures can also be implemented in a more separated orintegrated manner, or even removed or rendered as inoperable in certaincases, as is useful in accordance with a particular application.Additionally, any signal arrows in the drawings/Figures should beconsidered only as exemplary, and not limiting, unless otherwisespecifically noted.

It should be understood that the inventive concepts disclosed herein arecapable of many other modifications. To the extent such modificationsfall within the scope of the appended claims and their equivalents, theyare intended to be covered by this patent. It should also be understoodthat the term “a” as used herein generally means “one or more” and isnot intended to be construed in a singular sense. In addition, theoperations described in connection with the methods of the disclosureneed not necessarily be executed in the sequence described, as they maybe executed in a different sequence consistent with the principles ofthe disclosure.

What is claimed is:
 1. A cannula, comprising: a first portion formedfrom a first material having a selected rigidity, comprising: a proximalend having a flange; a distal end; and a passage from the proximal endto the distal end; and a second portion formed from a second materialskied permanently fixed to the first portion and comprising: a proximalend; a distal end; and a first dam formed in the passage of the firstportion between the proximal end and the distal end of the secondportion.
 2. The cannula of claim 1, further comprising a membranelocated in the second portion having a selected flexibility.
 3. Thecannula of claim 2, wherein the membrane further comprises at least oneof a slot and an opening.
 4. The cannula of claim 1, wherein the distalend of the second portion further comprises one or more of a flange or alength that extends beyond the distal end of the first portion.
 5. Thecannula of claim 1, wherein the second portion partially overlaps thefirst portion.
 6. The cannula of claim 5, wherein the second portionpartially overlaps the first portion, wherein the second portionincludes a thread.
 7. The cannula of claim 1, wherein the second portioncomprises a feature at the distal end for engaging the distal end of thefirst portion.
 8. The cannula of claim 1, wherein the first portioncomprises a thread.
 9. The cannula of claim 8, wherein the threadextends from the flange to the distal end of the cannula.
 10. Thecannula of claim 9, wherein the second portion extends to wrap around anouter surface of the first portion.
 11. The cannula of claim 8, whereinthe distal end of the first portion is extended from the thread.
 12. Thecannula of claim 11, wherein the second portion extends to wrap aroundan outer surface of the first portion.
 13. The cannula of claim 8,wherein the second portion extends to wrap around an outer surface ofthe first portion.
 14. The cannula of claim 1, wherein the secondportion comprises a thermoplastic elastomer.
 15. The cannula of claim 1,wherein the second portion extends to wrap around an outer surface ofthe first portion.
 16. The cannula of claim 1, wherein the first portionhas an outer radius and the second portion has an inner radius, andwherein a ratio of the outer radius to the inner radius is selected tominimize the overall size of the cannula.
 17. The cannula of claim 1,wherein the dam further comprises at least one slit.
 18. The cannula ofclaim 17, further comprising a membrane located in the second portionhaving a selected flexibility.
 19. The cannula of claim 18, wherein themembrane further comprises at least one of a slot and an opening. 20.The cannula of claim 19, wherein at least one dam slit and at least onemembrane slot do not align.